1. Field of the Invention
The present invention relates to a method of coating surfaces of various materials with control-releasable nitrogen monoxide using a catecholamine, and, more particularly, to technology of preparing a coating film containing a diazeniumdiolate functional group on a surface of a material using a catecholamine.
2. Discussion of Related Art
Nitrogen monoxide (NO) is a bio-regulatory material exhibiting potent medical effects in various fields, which was selected as the “molecule of the year” by the US journal Science in 1992, and was a main topic for the Nobel Prizes in physiology and medicine in 1998. Nitrogen monoxide serves as a signal transduction material or a product formed by an immune response in a human body, and has various effects such as vasodilatation, neurotransmission, regulation of hair cycle, formation of reactive nitrogen-containing intermediates, regulation of penile erections, antibacterial effects, antiviral effects and wound healing. Especially, nitrogen monoxide has a very short in vivo half-life of less than 6 seconds, and exhibits its various effects when it is present in a gaseous state. Therefore, nitrogen monoxide has an advantage in that its effects are exhibited only in a local site in which it is released in vivo, and thus is highly applicable as a body-implantable material.
There are various kinds of compounds in which nitrogen monoxide can be released from a surface of the body-implantable material. For example, such compounds include an organic nitrate or ester, an iron-nitrosyl complex, sydnonimine, a C-nitroso compound, S-nitrosothiol (R—S—NO), a 1-substituted diazen-1-ium-1,2-diolate, etc. However, conventional techniques for physically adsorbing the various compounds onto a surface of an implantable medical device have problems in that nitrogen monoxide may be released in sites rather than a desired local site since its coatability is unstable under in vivo conditions, and may not be released at a sufficient amount. Also, a xerogel, to which a diazeniumdiolate formed by a conventional sol-gel synthesis method using an aminosilane is attached, has problems in that it is very expensive and difficult to synthesize the aminosilane, and its coating thickness is high. Also, a conventional method of attaching a nitrogen monoxide transmitter containing a sulfur group to a surface of a metal using a self-assembled monolayer has an advantage in that it is applicable only to certain metals.
Therefore, there has been an increasing interest in methods by which a large amount of nitrogen monoxide can be attached to any materials with high stability to effectively release the nitrogen monoxide. Accordingly, the formed coating film for releasing nitrogen monoxide has characteristics in that its thickness should not be so large as to cause inconvenience in applying body-implantable materials, and is simplified and inexpensive to be industrially applicable. Also, the coating film should not exhibit toxicity at a cellular level, and its concentration and release time should be easily controlled.
However, there has been no report on a method of preparing a nitrogen monooxide-releasing coating film satisfying the above-described requirements so far.